package com.kuang.dao;


import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

//dao操作数据库公共类
public class BaseDao {
    private static String driver;
    private static String url;
    private static String username;
    private static String password;

//    静态代码块 类加载在就初始化
    static{
        Properties properties = new Properties();
//        通过类加载器获取对应资源
        InputStream is = BaseDao.class.getClassLoader().getResourceAsStream("db.properties");
        try {
            properties.load(is);
        } catch (IOException e) {
            e.printStackTrace();
        }
        driver=properties.getProperty("driver");
        url=properties.getProperty("url");
        username=properties.getProperty("username");
        password=properties.getProperty("password");
    }
//    获取数据库链接
    public static Connection getConnection(){
        Connection connection=null;
        try {
            Class.forName(driver);
            connection=DriverManager.getConnection(url, username, password);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return connection;
    }
//    编写查询公共类
    public static ResultSet execute(Connection connection,PreparedStatement preparedStatement, ResultSet resultSet,String sql,Object[] params) throws SQLException {
//      预编译的sql在后面直接执行就行
         preparedStatement = connection.prepareStatement(sql);
        for (int i = 0; i <params.length ; i++) {
//            setObject，占位符从一开始，但是我们数组从0开始
            preparedStatement.setObject(i+1,params[i]);
        }
         resultSet = preparedStatement.executeQuery();
        return resultSet;
    }
//    编写增删改公告方法
        public static int execute(Connection connection,PreparedStatement preparedStatement,String sql,Object[] params) throws SQLException {
             preparedStatement = connection.prepareStatement(sql);
            for (int i = 0; i <params.length ; i++) {
        //            setObject，占位符从一开始，但是我们数组从0开始
                preparedStatement.setObject(i+1,params[i]);
            }
            int updateRows = preparedStatement.executeUpdate();
            return updateRows;
        }
//        关闭连接释放资源
    public static boolean closeResource(Connection connection,PreparedStatement preparedStatement,ResultSet resultSet) {
        boolean flag = true;
        if (resultSet != null) {
            try {
                resultSet.close();
                //GC回收
                resultSet = null;
            } catch (SQLException e) {
                e.printStackTrace();
                flag = false;
            }
        }
        if (preparedStatement != null) {
            try {
                preparedStatement.close();
                //GC回收
                preparedStatement = null;
            } catch (SQLException e) {
                e.printStackTrace();
                flag = false;
            }
        }
        if (connection != null) {
            try {
                connection.close();
                //GC回收
                connection = null;
            } catch (SQLException e) {
                e.printStackTrace();
                flag = false;
            }
        }
        return flag;
    }

}
